光電化學太陽電池為新一代的太陽電池，具有可撓、製造簡單、成本便宜等優勢，但如使用釕錯合物染料，不僅價格昂貴、技術受制於人，且因只吸收特定波長範圍太陽光，使得整體效率以及製作成本仍無法取代現今矽太陽電池。本論文希望藉由半導體量子點取代染料敏化太陽電池中釕錯合物染料，並提升其光電性能。半導體量子點合成上比釕錯合物便宜許多以外，量子點具有量子侷限效應，隨著調整粒徑大小，吸收之能隙寬（energy gap）也隨之改變，所以可以藉此特性製造高效率之量子點敏化太陽電池（quantum dot sensitized solar cells, QDSSC）取代傳統染料敏化太陽電池。
本研究方式是使用時間獨立（time independent）與時間相依（time dependent）的密度泛函理論（density functional theory, DFT），搭配B3LYP（Becke, three-parameter, Lee-Yang-Parr）交換相關泛函。由於PbS塊材的能隙寬約為0.37eV，所以當PbS量子點發生量子侷限效應時，能隙寬剛好會從紅外光涵蓋到可見光。所以首先建立不同尺寸的PbS量子點，接著計算PbS量子點的各種光學性質，如能隙寬、電子軌道、態密度分布（density of states, DOS）、吸收光譜等。另外，利用Marcus Theory去計算電子傳輸速率，評比量子點較好的電子傳輸速率優勢。接著分析PbS原子團在三氯甲烷中的溶劑效應，然後討論PbS原子團在TiO2表面吸附情形，以及利用分子軌域圖，觀察光電激發後電子傳遞情形，從PbS量子點往TiO2傳遞路徑。
最後，我們拿實驗值和模擬值做比較，証明兩者數值皆符合量子侷限效應，表示藉由控制PbS量子點的粒徑，即可增加PbS量子點吸光範圍，且能隙寬皆在紅外線擴及可見光範圍中。此外，在TiO2的表面吸附電子軌域圖也可以看出，當PbS量子點激發後電子會往TiO2傳遞，故可以數種奈米科技增加QDSSC中太陽光的吸收率與光電轉換效率。

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